Hi @TahsinGökçeer ...
Thanks for clarifying that you are wanting to import your content from one Canvas environment into another Canvas environment That being said, yes, you would first want to export your course content, and then you'd import the *.imscc file into the course in the other Canvas environment.
Out of curiosity, for the Canvas shell where you are trying to import your course export *.imscc file, is that in a paid Canvas environment, or are you using the FFT (Free For Teacher) Canvas environment? If you are using the FFT environment, there is limit of 500 MB per course, and this cannot be changed. If your exported *.imscc file is larger than that, then that is the issue with why your file isn't uploading. You'd need to slim down your course in some way to get it below 500 MB. You can read more about the differences between a paid Canvas environment vs. a FFT environment here:
Canvas Free-for-Teacher FAQ
Check out the linked PDF near the top of the article to see a comparison table.
I hope this will be helpful to you. Let Community members know if you have any other questions about this...thanks!